Bipolar electrosurgical instrument with movable electrode and related systems and methods

ABSTRACT

An electrosurgical device is provided that includes a handset having a shaft extending therefrom, a pair of active electrodes at a distal end of the shaft, and a movable, electrically floating electrode selectively positionable between the active electrodes. The floating electrode, when positioned to contact tissue between the active electrodes, modifies the electrosurgical current flows through tissue. The resultant modified current flows enables a surgeon to more effectively to control tissue desiccation by focusing electrosurgical energy toward targeted tissue and by reducing peripheral current flows. Embodiments are provided wherein the active electrodes include cooling provisions. Related electrosurgical systems and method of use are also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 14/335,233, filed on Jul. 18, 2014, which claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/884,573, filed on Sep. 30, 2013, the entire disclosures of each of which are incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to a bipolar electrosurgical instrument configured to provide controlled deep tissue desiccation. More particularly, the present disclosure relates to an electrosurgical instrument that includes a pair of electrodes and a movable floating electrode that enables a surgeon to effectively control tissue desiccation.

Background of Related Art

Electrosurgical devices, such as surface tissue desiccation devices are well known in the medical arts and typically include a handset with an on/off switch, a shaft, and at least one electrode operatively coupled to a distal end of the shaft that is configured to perform an electrosurgical procedure, such as surface or deep tissue desiccation. Such electrosurgical devices utilize electrical energy to effectuate hemostasis and desiccation by heating the tissue and blood vessels. Such devices include electrocautery pencils, forceps, and probes of various types and configurations from a number of different manufacturers. The algorithms used with these electrosurgical devices in surgical treatments typically seek to provide a desired amount of delivered energy in accordance with the power level and duration specified by the surgeon.

Electrosurgical devices which utilize this electrical energy for performing deep tissue coagulation and desiccation during orthopedic procedures, such as spinal and joint replacement surgery, may have drawbacks which influence surgical outcomes. For example, a typical issue is the inability of a surgeon to reliably and selectively control tissue treatment depth during desiccation procedures. It has been observed that during desiccation procedures, surgeons tend to manipulate tissue with the electrodes of the device to retract and separate tissue. This technique, however, may extend operative times and/or cause unsatisfactory results due to varying contact area between the electrode and tissue as the instrument is manipulated.

SUMMARY

In view of the foregoing, an electrosurgical instrument that includes a pair of electrodes and a movable floating electrode that enables a surgeon to effectively control tissue desiccation, and associated systems and methods of use, would be a welcome advance in the state of the art.

Embodiments of the present disclosure are described in detail with reference to the drawing figures wherein like reference numerals identify similar or identical elements. As used herein, the term “distal” refers to the portion that is being described which is further from a user, while the term “proximal” refers to the portion that is being described which is closer to a user.

As it is used herein, “electrosurgical procedure” generally refers to any electrosurgical procedure involving any form of energy, such as, for example, microwave energy and radiofrequency (RF) energy.

In one aspect of the present disclosure, an electrosurgical instrument is provided. The electrosurgical instrument includes a handle having a shaft extending distally therefrom, a first active electrode and a second active electrode disposed in spaced relation on a distal end of the shaft, and a floating electrode or electrode selectively positionable between an extended position where the floating electrode is disposed within an area between the first active electrode and a second active electrode, and a retracted position where the floating electrode is removed from the area between the first active electrode and a second active electrode. The first active electrode and a second active electrode may be configured to couple to a source of electrosurgical energy. The first active electrode, the second active electrode, and the floating electrode may each include a tissue-contacting surface.

In some embodiments, when the floating electrode is in the extended position, the tissue-contacting surfaces of the first active electrode, the second active electrode, and the floating electrode lie substantially in the same plane. The active electrodes may be configured to operate in a bipolar mode of operation.

In other embodiments, the electrosurgical instrument includes a coolant supply conduit configured to deliver coolant to the first active electrode and the second active electrode, and a coolant return conduit configured to remove coolant from the first active electrode and the second active electrode. In yet other embodiments, the first and second active electrodes are each in thermal communication with a heat pipe that is configured to draw heat from the first and second active electrodes to the ambient atmosphere.

The electrosurgical instrument may include a drive mechanism having a drive member movable along a longitudinal axis of the shaft between a first position and a second position, a cam slot defined in a distal end of the drive member, and a follower fixed to the floating electrode and configured to operably engage the cam slot. When the drive member is in a first position the floating electrode is in the extended position, and wherein when the drive member is in a second position, the floating electrode is in the retracted position.

In an alternative embodiment, the drive mechanism may include a drive member movable along a longitudinal axis of the shaft between a first position and a second position and an electrode guide. The electrode guide may include an elongated entrance opening defined at an entrance end of the electrode guide having an entrance direction and an elongated exit opening defined at an exit end of the electrode guide and having an exit direction different from the entrance direction. The electrode guide may include a channel joining the entrance opening and the exit opening and include an elbow transitioning the channel from the entrance direction to the exit direction. The cross section of the channel at the elbow may have an elongated rectangular shape, and the cross section of the channel at the exit opening may have a curved elongated rectangular shape. The floating electrode may be formed from a strip of flexible material positioned, in part, within the electrode guide, and operably coupled to a distal end of the drive member.

In another aspect of the present disclosure, an electrosurgical system is provided. The disclosed electrosurgical system includes an electrosurgical generator and an electrosurgical instrument as described above. The electrosurgical generator and the pair of electrodes may be configured to operate in a bipolar mode of operation.

In yet another aspect of the present disclosure, a method for electrosurgically treating tissue is provided. The disclosed method includes the steps of providing an electrosurgical device as described above, applying the first active electrode and the second active electrode to tissue, and delivering electrosurgical energy to tissue via the first active electrode and the second active electrode. The method may include the steps of applying the floating electrode to tissue and/or removing the floating electrode from tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described hereinbelow with references to the drawings, wherein:

FIG. 1 is a perspective view of a system for electrosurgically treating tissue according to an embodiment of the present disclosure;

FIG. 2A is a schematic view of bipolar electrodes and a floating electrode in a raised configuration in accordance with an embodiment of the present disclosure;

FIG. 2B is a schematic view of bipolar electrodes and a floating electrode in a lowered configuration in accordance with an embodiment of the present disclosure;

FIG. 2C is a schematic view of bipolar electrodes and a bifurcated electrode having a fixed potential in a lowered configuration in accordance with another embodiment of the present disclosure;

FIG. 2D is a schematic view of bipolar electrodes and a bifurcated electrode having a variable potential in a lowered configuration in accordance with yet another embodiment of the present disclosure;

FIG. 3 is a view of an electrosurgical instrument in accordance with an embodiment of the present disclosure having a circulating coolant system;

FIG. 4 is a view of an electrosurgical instrument in accordance with an embodiment of the present disclosure having a heat pipe coolant system;

FIG. 5A is a detail, side view of a floating electrode and a drive member of an electrosurgical instrument in accordance with an embodiment of the present disclosure;

FIG. 5B is a detail, perspective view of a floating electrode and a drive member of the FIG. 5A embodiment;

FIG. 5C is an end view of a drive member of a floating electrode and a drive member of the FIG. 5A embodiment;

FIG. 6A is a detail, side view of a floating electrode and a drive member of an electrosurgical instrument in accordance with another embodiment of the present disclosure;

FIG. 6B is a detail, perspective view of a floating electrode and a drive member of the FIG. 6A embodiment;

FIG. 7A is a side view of a deployable floating electrode in a raised position in accordance with yet another embodiment of the present disclosure;

FIG. 7B is a side view of a deployable floating electrode in a lowered position in accordance with the FIG. 7A embodiment;

FIG. 7C is a top view of a floating electrode guide in accordance with the FIG. 7A embodiment;

FIG. 7D is a bottom view of a floating electrode guide in accordance with the FIG. 7A embodiment;

FIG. 7E is a perspective view of a floating electrode and guide in accordance with the FIG. 7A embodiment;

FIG. 7F is a section view of a floating electrode guide in accordance with the FIG. 7A embodiment; and

FIG. 7G is another section view of the floating electrode guide in accordance with the FIG. 7A embodiment.

DETAILED DESCRIPTION

Particular embodiments of the present disclosure are described hereinbelow with reference to the accompanying drawings; however, it is to be understood that the disclosed embodiments are merely examples of the disclosure, which may be embodied in various forms. Well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. In this description, as well as in the drawings, like-referenced numbers represent elements which may perform the same, similar, or equivalent functions; the term “proximal,” as is traditional, shall refer to the end of the instrument that is closer to the user, while the term “distal” shall refer to the end that is farther from the user. In addition, references to positive (+) and negative (−) are for illustrative purposes only, and it is to be understood that the polarity of the described elements may vary over time in accordance with the alternating current nature of electrosurgical energy.

Referring to FIG. 1, there is shown a perspective view of an electrosurgical system 1 including a generator 5 having a controller 7, and an electrosurgical instrument 10 for electrosurgically treating tissue according to an embodiment of the present disclosure. A coolant unit 27 is provided for delivering fluid to electrodes 12, 14 of electrosurgical instrument 10. Cooling unit 27 includes a coolant reservoir 28 in which a supply of coolant may be maintained, such as, without limitation, deionized water, glycol, saline, and the like. Cooling unit 27 may include a coolant pump 25 that is configured to circulate coolant between reservoir 28 and instrument 10 via coolant supply conduit 26 and coolant return conduit 24. Coolant supply conduit 26 and coolant return conduit 24 are electrically isolated from one other. In some embodiments, the cooling fluid circulated through coolant supply conduit 26 and coolant return conduit 24 is a non-conducting or a low conductive substance.

Continuing with reference to FIG. 1, generator 5 is configured to generate and deliver electrosurgical energy, e.g., radio frequency energy, to active electrodes 12 and 14, for performing electrosurgical procedures. The electrosurgical procedures may include cutting, cauterizing, coagulating, desiccating, and fulgurating tissue; all of which may employ RF energy. Generator 5 may be configured for monopolar and/or bipolar modes of operation. For illustrative purposes, generator 5 and, hence, system 1, is shown configured for a bipolar mode of operation.

Generator 5 includes one or more processors 8 that are in operative communication with controller 7 and configured to transmit electrosurgical energy, which may be in the form of a wave or signal/pulse, via cable 6 to instrument 10. Controller 7 and/or processor 8 may include one or more control algorithms that regulate the delivery of electrosurgical energy to tissue in accordance with an impedance of an electrode-tissue interface. One or more data lookup tables accessible by controller 7 and/or processor 8 may utilized to store relevant information relating to impedance and/or energy delivery. This information relating to impedance and/or pressure may be acquired empirically and/or calculated utilizing one or more suitable equations.

In the embodiment illustrated in FIG. 1, instrument 10 is shown as a bipolar electrocautery pencil (such as the one described in commonly-owned U.S. Pat. No. 7,621,909 to Buchman II, et al.) that includes a proximal handle 15 and a distal shaft 16. Handle 15 includes a slide actuator 19 that is configured to selectively position a movable, electrically floating electrode 11 between active electrode 12 and active electrode 14. Floating electrode 11 is formed from conductive material, and may be lowered (extended) and raised (retracted) between electrodes 12 and 14 to alter the energy field formed therebetween during electrosurgical procedures. In the embodiment illustrated in FIG. 1, moving slide actuator 19 distally causes floating electrode 11 to lower between electrodes 12 and 14. Conversely, moving slide actuator 19 proximally retracts floating electrode 11. In other embodiments, floating electrode 11 may be lowered by moving slide actuator 19 proximally and raised by moving slide actuator 19 distally. In yet other embodiments, a trigger actuator, a rotary actuator, or motorized actuator may be employed to extend and retract floating electrode 11.

Shaft 16 extends distally from handle 15, and active electrode 12 and active electrode 14 are disposed at a distal end 17 of shaft 16. In some embodiments, a guide 18 is operatively associated with floating electrode 11 to facilitate the selective positioning thereof.

In some embodiments, instrument 10 may be configured for a monopolar mode of operation. In these embodiments, one or both of the active electrodes 12 or 14 is configured to deliver monopolar electrosurgical energy to tissue, and a return pad (not explicitly shown) may be positioned on a patient and utilized as a return electrode.

Advantageously, use of the movable floating electrode 11 in accordance with the present disclosure enables a surgeon to selectively control the intensity and/or depth of the electrosurgical effect from the adjacent electrodes 12, 14. This advantage is illustrated in detail with reference to FIGS. 2A and 2B. As shown in FIG. 2A, an electrode assembly 30 includes a first electrode 32 and a second electrode 34 positioned in a fixed, spaced relation to one another and coupled to a source of electrosurgical energy 35 by conductors 36, and a movable, floating electrode 31 selectively positioned in a raised position. The electrodes 32, 34 are brought into contact with tissue T at the targeted area, and the source of electrosurgical energy 35 is activated. Electrosurgical energy flows between electrodes 32, 34 forming a radiating pattern 37 which radiates between electrodes 32, 34. As seen in FIG. 2A, radiating pattern 37 forms not only a relatively direct path directly between electrodes 32, 34, but also radiates away from electrodes 32, 34, which may cause undesired tissue effects peripheral to the targeted tissue area.

Turning to FIG. 2B, where floating electrode 31 is shown in a lowered position in contact with tissue T, a modified radiating pattern 38 is formed when electrosurgical energy is delivered by electrodes 32, 34. As can be seen in FIG. 2B, the modified radiating pattern 38 converges at floating electrode 31 to focus more precisely to the targeted tissue site. In addition, peripheral radiation is decreased. It is believed that the floating electrical potential of floating electrode 31, when positioned between electrodes 32, 34, is determined by the impedance(s) if the tissue T between the electrodes 32, 34 and the electrosurgical current lowing therebetween. Thus the potential of floating electrode 31 falls between the voltages of electrodes 32, 34, which, in turn, creates the modified radiating pattern 38 as illustrated in FIG. 2B.

Advantageously, a surgeon may utilize floating electrode 31 as an additional tool surface with which to dissect tissue T. For example, a surgeon may extend or lower floating electrode 31 and manipulate the entire instrument, bringing electrodes 32, 34 and floating electrode 31 into, and out of, contact with tissue T to work the surgical site. In another example, a surgeon may bring electrodes 32, 34 into substantially continuous contact with tissue T, and manipulate floating electrode 31 up and down using an actuator (e.g., finger trigger or slide as described herein). In yet another example, a surgeon may variously utilize combinations of the above techniques, compound motions, and the like, as required by the instant surgical objective.

In another aspect of the present disclosure illustrated in FIG. 2C, an electrosurgical instrument 130 includes a movable active electrode 131 that is selectively positionable between fixed active electrodes 132, 134. Active electrode 131 includes two conductive sections 141 and 142 that are electrically isolated by an insulator 143 disposed therebetween. An electrosurgical generator 135 is coupled to electrodes 132, 134 by conductors 136, 137, respectively. Conductive sections 141 and 142 are electrically coupled to fixed active electrodes 132, 134 by conductors 146, 147, respectively. By this arrangement, negative movable active electrode 142 is positionable adjacent to positive fixed active electrode 132, and negative movable active electrode 141 is positionable adjacent to positive fixed active electrode 134. Advantageously, the alternating polarity arrangement of the FIG. 2C electrodes enhances the focus of modified radiating pattern 138, which effectively creates a dual bipolar ablation zone.

In yet another aspect of the present disclosure illustrated in FIG. 2D, an electrosurgical instrument 230 includes a movable active electrode 231 that is selectively positionable between fixed active electrodes 232, 234. Active electrode 231 includes two conductive sections 241 and 242 that are electrically isolated by an insulator 243 disposed therebetween. An electrosurgical generator 235 is coupled to electrodes 232, 234 by conductors 236, 237, respectively. Conductive sections 241 and 242 are electrically coupled to a dual-channel intensity control 250 by conductors 244, 248, respectively. Electrosurgical generator 235 is coupled to intensity control 250 by conductors 240 and 247. Intensity control 250 may be continuously variable, and may be user controlled by, e.g., a user interface control such as rotary control (knob) or a linear control (slider or lever). In some embodiments, intensity control 250 may be controlled by a processor and/or in accordance with a tissue parameter, such as, without limitation, tissue temperature, tissue impedance, ablation time, tissue hydration, and/or a rate of change of the same. In some embodiments, intensity control 250 may have an effective range of 0% to 100% of the electrosurgical signal generated by generator 235. In other embodiments, intensity control 250 may have an effective range of −100% to 100% of the electrosurgical signal generated by generator 235. In yet other embodiments, intensity control 250 may have an effective range of 0% to greater than 100% or +/−100% of the electrosurgical signal (e.g., imparting gain to the electrosurgical signal).

In another aspect of the present disclosure illustrated in FIG. 3, an electrosurgical instrument 40 includes a coolant supply conduit 47 configured to deliver coolant to first electrode 42, and to second electrode 44. Electrodes 42, 44 are coupled to a source of electrosurgical energy 45 by conductors 46. As shown, electrodes 42 and 44 each include a cooling chamber 55 and 56, respectively, defined therein. Coolant supply conduit 47 is coupled at a distal end thereof to cooling chamber 55 to deliver coolant thereto. An intermediate outflow conduit 50 having a distal opening 53 disposed within cooling chamber 55 is configured to receive coolant exiting from cooling chamber 55. Coolant flows through intermediate outflow conduit 50 to a coupler 51 which is configured to join intermediate outflow conduit 50 and intermediate inflow conduit 52 in fluid communication. In some embodiments, such as that illustrated in FIG. 3, coupler 51 is u-shaped. In some embodiments, coupler 51 is formed from electrically and/or thermally insulative material. Intermediate inflow conduit 52 receives coolant from intermediate outflow conduit 50 via coupler 51, and, in turn, delivers coolant to second electrode 44 via opening 54 disposed within cooling chamber 56. Coolant return conduit 48 is in fluid communication with cooling chamber 56 of electrode 44 to receive coolant exiting from cooling chamber 56 and, in turn, exhausts coolant from instrument 40 to a reservoir, drain, etc.

In other embodiments, the coolant supply may be arranged in a parallel configuration whereby incoming coolant is divided (using, e.g., a “Y” coupling or a manifold) and directed to each electrode, and outgoing coolant from each electrode is joined at a combining junction and exits instrument 40 via coolant return conduit 48.

Instrument 40 includes a floating electrode 41 that is selectively extendible between electrode 42 and electrode 44. A follower 58 is joined to an upper portion of floating electrode 41 that is configured to ride within a cam slot 57 defined in a distal end of a drive member 43. Drive member 43 is configured to move longitudinally, e.g., distally and proximally, and includes a trigger 49 that facilitates manipulation of drive member 43 by a surgeon. As shown in the FIG. 3 embodiment, a distal movement of drive member 43 causes follower 58 to ride downward within cam slot 57, thereby moving floating electrode 41 into an extended, lowered, or deployed, position. Conversely, proximal movement of drive member 43 causes floating electrode 41 to move to a retracted or raised position. Instrument 40 may include ergonomic features, such as, without limitation, a handle (not explicitly shown), a pistol grip (not explicitly shown) or any other suitable features configured to facilitate grasping and use by a surgeon.

In another aspect of the present disclosure, an embodiment of an electrosurgical instrument 60 is shown in FIG. 4 which includes a first electrode 62 and a second electrode 64 disposed in electrical communication with an electrosurgical generator 65 via conductors 66. A movable floating electrode 61 includes a follower 78 that is configured to engage a cam slot 71 defined in a proximal portion of a drive member 63. Drive member 63 is configured to move distally and proximally, which translates into an up-and-down motion of floating electrode 61 through the cooperation of follower 78 and cam slot 71. Drive member 63 includes a trigger 69 or similar ergonomic feature to facilitate the actuation thereof by a surgeon. Instrument 60 may include ergonomic features, such as, without limitation, a handle 79 or any other suitable features intended to facilitate handling.

Instrument 60 includes a first heat pipe 67 having a hot end 73 that is in thermal communication with electrode 62 and a cool end 75, and a second heat pipe 68 having a hot end 74 that is in thermal communication with electrode 64 and a cool end 76. Heat pipes 67 and 68 may include a heat pipe construction which includes a sealed copper pipe having contained therein a quantity of fluid, such as water or ethanol, and/or a partial vacuum that is near or below the vapor pressure of the fluid. During use, some of the fluid will be in liquid phase and some will be in gas phase. As the hot ends 73, 74 of heat pipes 67, 68 are heated due to thermal effects relating to an electrosurgical procedure, the fluid inside heat pipes 67, 68 vaporizes and increases the vapor pressure therein. The latent heat of evaporation absorbed by the vaporization of the working fluid reduces the temperature at the hot ends 73, 74 of heat pipes 67, 68. The vapors migrate to the respective cool ends 75, 76 of heat pipes 67, 68 where they condense and revert to liquid phase, releasing the absorbed heat. A wick 72, 77 disposed, respectively, within an inner surface of heat pipes 67, 68, absorbs any liquid by capillary action and returns the liquid to the hot ends 73, 74 of heat pipes 67, 68 in an essentially continuous cycle. In some embodiments, cool ends 75, 76 of heat pipes 67, 68 are exposed to the ambient atmosphere, and may include one or more heat sinks (not shown) to facilitate the heat transfer cycle.

Turning to FIGS. 5A-5C, a detailed view of a drive mechanism 80 in accordance with the present disclosure is presented. Drive mechanism 80 is arranged such that a distal motion of an actuation ring 89 results a downward motion of the floating electrode 81. Drive mechanism 80 includes a drive member 83 having a cam slot 87 defined therein at a distal end thereof. As best seen in FIG. 5A, cam slot 87 is angled with respect to the longitudinal axis “A-A” of drive member 83 and has a distal end that is higher than the proximal end. The floating electrode 81 includes a follower 88 joined to an upper portion of the floating electrode 81 by an extension 86. In some embodiments, floating electrode 81, extension 86, and follower 88 may be integrally formed from sheet metal using a punching and/or stamping process. In some embodiments, floating electrode 81, extension 86, and follower 88 may be formed from stainless steel. Follower 88 is disposed at an angle with respect to floating electrode 81 which substantially corresponds to the angle of cam slot 87. In the FIGS. 5A-5C embodiments, where forward (distal) motion of the drive member 83 causes downward deployment of floating electrode 81, an actuation ring 89 may be provided to enable a surgeon to readily manipulate drive member 83 in either a distal or proximal direction.

In another embodiment depicted in FIGS. 6A and 6B, a drive mechanism 90 in accordance with the present disclosure is arranged such that proximal motion of an actuation trigger 99 results a downward motion of the floating electrode 91. Drive mechanism 90 includes a drive member 93 having a cam slot 97 defined therein at a distal end thereof. Here, cam slot 97 is angled with respect to the longitudinal axis “B-B” of drive member 93 such that the distal end of cam slot 97 is lower than the proximal end of cam slot 97. Floating electrode 91 includes a follower 98 joined to an upper portion of the floating electrode 91 by an extension 96. Follower 98 is disposed at an angle which substantially corresponds to the angle of cam slot 97. Rearward (proximal) motion of drive member 93 causes downward deployment of floating electrode 91. In this embodiment, trigger 99 is provided to enable the surgeon to intuitively manipulate drive member 93 in proximal direction to deploy floating electrode 91. A return spring 95 is provided which biases drive member 93 in a distal direction, thus when a surgeon releases pressure on trigger 99, drive member 93 is driven distally and floating electrode 91 is moved upwardly through the cooperation of follower 98 and cam slot 97.

Turning now to FIGS. 7A-7G, yet another embodiment of a drive mechanism 100 for a floating electrode 101 is presented. Floating electrode 101 is formed from a strip of flexible material, such as spring steel, Nitinol (or other shape memory metal), and/or a high-temperature-resistant composite material. A proximal end of floating electrode 101 is joined to a drive member 103 by a pin 102. Drive member 103 includes a thumb actuator 109 which is configured to be manipulated a surgeon to effectively lower and raise floating electrode 101. A distal portion of floating electrode 101 passes through an L-shaped electrode guide 108 having a channel 107 defined therein. Channel 107 includes an entrance 105 into which floating electrode 101 is introduced and an exit 106 through which floating electrode 101 extends toward tissue.

Electrode guide 108 includes a 90° transition elbow having a radius a which enables the distal portion of floating electrode 101, as it is advanced distally by drive member, to bend downwardly and thus extend into a lowered position between the bipolar electrodes (not explicitly shown). As can be seen in FIG. 7F, a cross section of channel 107 adjacent to radius a is substantially straight, enabling the flexible floating electrode 101 to remain flat and thus allowing floating electrode 101 to flex easily as it is advanced through radius a during deployment of floating electrode 101 into position between electrodes. As channel 107 approaches exit 106, the cross section of channel 107 become slightly curved as shown in FIGS. 7E and 7G. As flexible floating electrode 101 extends from exit 106, this curve is imparted to floating electrode 101 (FIG. 7E), which, in turn, provides rigidity and stiffness to the extended portion 110 of floating electrode 101.

In some embodiments, the inner surface of channel 107 and/or the outer surface of flexible floating electrode 101 may include a lubricious coating, such as, without limitation, polytetrafluoroethylene (PTFE).

The various embodiments disclosed herein may also be configured to work with robotic surgical systems and what is commonly referred to as “Telesurgery”. Such systems employ various robotic elements to assist the surgeon in the operating theatre and allow remote operation (or partial remote operation) of surgical instrumentation. Various robotic arms, gears, cams, pulleys, electric and mechanical motors, etc. may be employed for this purpose and may be designed with a robotic surgical system to assist the surgeon during the course of an operation or treatment. Such robotic systems may include remotely activatable active electrodes, a remotely positionable floating electrode, remotely steerable systems, remotely articulating surgical systems, wireless surgical systems, modular, or selectively configurable remotely operated surgical systems, etc.

The robotic surgical systems may be employed with one or more consoles that are next to the operating theater or located in a remote location. In this instance, one team of surgeons or nurses may prep the patient for surgery and configure the robotic surgical system with one or more of the instruments disclosed herein while another surgeon (or group of surgeons) remotely control the instruments via the robotic surgical system. As can be appreciated, a highly skilled surgeon may perform multiple operations in multiple locations without leaving his/her remote console which can be both economically advantageous and a benefit to the patient or a series of patients.

The robotic arms of the surgical system are typically coupled to a pair of master handles by a controller. The handles can be moved by the surgeon to produce a corresponding movement of the working ends of any type of surgical instrument (e.g., end effectors, graspers, knifes, scissors, etc.) which may complement the use of one or more of the embodiments described herein. The movement of the master handles may be scaled so that the working ends have a corresponding movement that is different, smaller or larger, than the movement performed by the operating hands of the surgeon. The scale factor or gearing ratio may be adjustable so that the operator can control the resolution of the working ends of the surgical instrument(s).

The master handles may include various sensors to provide feedback to the surgeon relating to various tissue parameters or conditions, e.g., tissue resistance due to manipulation, cutting or otherwise treating, pressure by the instrument onto the tissue, tissue temperature, tissue impedance, etc. As can be appreciated, such sensors provide the surgeon with enhanced tactile feedback simulating actual operating conditions. The master handles may also include a variety of different actuators for delicate tissue manipulation or treatment further enhancing the surgeon's ability to mimic actual operating conditions, such as contacting the active electrode to targeted tissue, extending and/or retracting the floating electrode, controlling the delivery of electrosurgical energy, and so forth.

While several embodiments of the disclosure have been shown in the drawings, it is not intended that the disclosure be limited thereto, as it is intended that the disclosure be as broad in scope as the art will allow and that the specification be read likewise. Therefore, the above description should not be construed as limiting, but merely as exemplifications of particular embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. 

1. (canceled)
 2. An electrosurgical instrument, comprising: a shaft; a first active electrode and a second active electrode disposed in spaced relation on a distal portion of the shaft, a tip of the first active electrode and a tip of the second active electrode disposed within a common plane; and a floating electrode selectively positionable between an extended position where the floating electrode is disposed within an area between the first active electrode and the second active electrode, and a retracted position where the floating electrode is removed from the area between the first active electrode and the second active electrode, wherein the floating electrode is parallel to the plane when the floating electrode is in both the extended position and in the retracted position, wherein when the floating electrode is in the extended position, at least a majority of the floating electrode is radially outside of a circumferential edge of the shaft.
 3. The electrosurgical instrument according to claim 2, wherein the tip of the first active electrode and the tip of the second active electrode extend radially outside of the circumferential edge of the shaft.
 4. The electrosurgical instrument according to claim 2, wherein the first active electrode is fixed from movement with respect to the second active electrode and with respect to the shaft.
 5. The electrosurgical instrument according to claim 2, wherein when the floating electrode is in the extended position, the first active electrode is located on a first lateral side of the floating electrode and the second active electrode is located on a second lateral side of the floating electrode, the first lateral side of the floating electrode being opposite from the second lateral side of the floating electrode.
 6. The electrosurgical instrument according to claim 2, wherein when the floating electrode is in the extended position, a tissue-contacting surface of the first active electrode, a tissue-contacting surface of the second active electrode, and a tissue-contacting surface of the floating electrode lie substantially in the same plane.
 7. The electrosurgical instrument according to claim 2, further comprising: a coolant supply conduit configured to deliver coolant to the first active electrode and the second active electrode; and a coolant return conduit configured to remove coolant from the first active electrode and the second active electrode.
 8. The electrosurgical instrument according to claim 2, further comprising a drive mechanism, including: a drive member movable along a longitudinal axis defined by the shaft between a first position and a second position; a cam slot defined in a distal end of the drive member; and a follower fixed to the floating electrode and configured to operably engage the cam slot, wherein when the drive member is in a first position, the floating electrode is in the extended position and wherein when the drive member is in a second position the floating electrode is in the retracted position.
 9. The electrosurgical instrument according to claim 2, wherein a distal-most end of the floating electrode is between distal portions of the first active electrode and the second active electrode when the floating electrode is in a fully retracted position.
 10. The electrosurgical system according to claim 1, wherein the floating electrode is movable relative to the first active electrode in a direction that is perpendicular with respect to a longitudinal axis defined by the shaft.
 11. The electrosurgical instrument according to claim 2, wherein the floating electrode is parallel to the tip of the first active electrode and the tip of the second active electrode while the floating electrode moves between the extended position and the retracted position.
 12. The electrosurgical instrument according to claim 2, wherein the floating electrode is disposed in non-pivotable relation relative to the shaft.
 13. An electrosurgical instrument, comprising: a shaft defining a longitudinal axis; a first active electrode and a second active electrode disposed in spaced relation on a distal portion of the shaft; and a floating electrode selectively positionable between an extended position where the floating electrode is disposed within an area between the first active electrode and the second active electrode, and a retracted position where the floating electrode is displaced from the area between the first active electrode and the second active electrode, wherein the floating electrode is only movable relative to the first active electrode in a direction that is perpendicular to the longitudinal axis.
 14. The electrosurgical instrument according to claim 13, wherein a tip of the first active electrode and a tip of the second active electrode extend radially outside of a circumferential edge of the shaft.
 15. The electrosurgical instrument according to claim 14, wherein when the floating electrode is in the extended position, at least a majority of the floating electrode is radially outside of the circumferential edge of the shaft.
 16. The electrosurgical instrument according to claim 13, wherein the first active electrode is immovable with respect to the second active electrode and with respect to the shaft.
 17. The electrosurgical system according to claim 13, wherein when the floating electrode is in the extended position, a tissue-contacting surface of the first active electrode, a tissue-contacting surface of the second active electrode, and a tissue-contacting surface of the floating electrode lie substantially in the same plane.
 18. A method for electrosurgically treating tissue, comprising: applying a first active electrode and a second active electrode of an electrosurgical surgical instrument to tissue; delivering electrosurgical energy to tissue via the first active electrode and the second active electrode; moving a floating electrode of the electrosurgical instrument from an extended position to a retracted position in a direction parallel to a tip of the first active electrode and a tip of the second active electrode, and within a plane that includes the tip of the first active electrode and the tip of the second active electrode, while moving the floating electrode in a direction that is perpendicular to a longitudinal axis defined by a shaft of the electrosurgical instrument; and applying the floating electrode to tissue.
 19. The method for electrosurgically treating tissue according to claim 18, wherein when the floating electrode is in the extended position, at least a majority of the floating electrode is radially outside of a circumferential edge of the shaft.
 20. The method for electrosurgically treating tissue according to claim 18, further comprising dissecting tissue using the floating electrode. 